French colonial officials wanted fewer rats in Hanoi, so they paid people for rat tails. The people responded by cutting off the tails—and keeping the rats alive so they could make more rats.
Hanoi Had a Rat Problem
At the turn of the 20th century, French colonial authorities were modernizing Hanoi.
Part of that modernization included a sewer system.
Unfortunately, those sewers also created an excellent underground habitat for rats.
With fears of bubonic plague increasing, officials wanted the rats gone.
Enter the Rat Bounty
Authorities hired rat catchers, but the rodents kept coming.
So officials introduced an incentive.
People could receive money for killing rats.
To prove the kill without requiring officials to handle entire rat carcasses, collectors could present the rat’s tail.
That seemed efficient.
Until officials began seeing something strange.
Live rats without tails.
Congratulations. You Just Invented Rat Farming.
People had figured out the obvious loophole.
Why kill a rat when you could cut off its tail, collect the bounty and release the animal so it could reproduce?
Reports even emerged of people breeding rats to create a continuing supply of profitable tails.
The government had attempted to create an incentive for eliminating rats.
Instead, it created an incentive for producing them.
Problem solved.
…You clearly haven’t watched Ugly History before.
Eventually the bounty program was abandoned.
History can be ugly.
But this? This was ridiculous.
Key Facts
- Event: Great Hanoi Rat Massacre
- Date: 1902
- Location: Hanoi, French Indochina — present-day Vietnam
- Problem: Rats and plague fears
- Government solution: Rat bounty
- Proof required: Rat tails
- Unintended consequence: Tailless rats and rat breeding
